[Bug tree-optimization/56982] [4.8 Regression] Bad optimization with setjmp()
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=56982 Richard Biener rguenth at gcc dot gnu.org changed: What|Removed |Added Status|ASSIGNED|RESOLVED Resolution|--- |FIXED Target Milestone|4.8.4 |4.9.0 Known to fail||4.8.4 --- Comment #18 from Richard Biener rguenth at gcc dot gnu.org --- wontfix for 4.8, the fix triggered very many latent issues.
[Bug tree-optimization/56982] [4.8 Regression] Bad optimization with setjmp()
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=56982 Richard Biener rguenth at gcc dot gnu.org changed: What|Removed |Added Target Milestone|4.8.3 |4.8.4 --- Comment #17 from Richard Biener rguenth at gcc dot gnu.org --- GCC 4.8.3 is being released, adjusting target milestone.
[Bug tree-optimization/56982] [4.8 Regression] Bad optimization with setjmp()
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56982 --- Comment #15 from Bernd Edlinger bernd.edlinger at hotmail dot de --- (In reply to Mikael Pettersson from comment #14) Your example is invalid C. Referring to WG14 n1494.pdf (there may be more recent C1x documents, but it's the one I had available right now): - you violate 7.13.1.1 which specifies where setjmp() may be called, an assignment statement is not one of the permitted contexts - more importantly, your auto variable a is not volatile-qualified, which means that its value is indeterminate after the longjmp (7.13.2.1). Please fix these issues and check again if it yields wrong results. Thanks for pointing that out. When I add volatile to the auto variable, the code is OK.
[Bug tree-optimization/56982] [4.8 Regression] Bad optimization with setjmp()
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56982 --- Comment #13 from Bernd Edlinger bernd.edlinger at hotmail dot de --- Created attachment 30431 -- http://gcc.gnu.org/bugzilla/attachment.cgi?id=30431action=edit another example of wrong compilation This is another example where the optimization can go wrong. The attached program produces expected results if compiled with -O0: x=0, a=1 x=1, a=1 a=1 But if compiled with -O3 and if the value a is placed in a register the result is like this: x=0, a=1 x=1, a=0 a=0 That is because longjmp has more semantic than just a branch: It branches to the setjmp, and restores all callee saved registers to the previos value.
[Bug tree-optimization/56982] [4.8 Regression] Bad optimization with setjmp()
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56982 --- Comment #14 from Mikael Pettersson mikpe at it dot uu.se --- (In reply to Bernd Edlinger from comment #13) Created attachment 30431 [details] another example of wrong compilation This is another example where the optimization can go wrong. The attached program produces expected results if compiled with -O0: x=0, a=1 x=1, a=1 a=1 But if compiled with -O3 and if the value a is placed in a register the result is like this: x=0, a=1 x=1, a=0 a=0 That is because longjmp has more semantic than just a branch: It branches to the setjmp, and restores all callee saved registers to the previos value. Your example is invalid C. Referring to WG14 n1494.pdf (there may be more recent C1x documents, but it's the one I had available right now): - you violate 7.13.1.1 which specifies where setjmp() may be called, an assignment statement is not one of the permitted contexts - more importantly, your auto variable a is not volatile-qualified, which means that its value is indeterminate after the longjmp (7.13.2.1). Please fix these issues and check again if it yields wrong results.
[Bug tree-optimization/56982] [4.8 Regression] Bad optimization with setjmp()
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56982 Bug 56982 depends on bug 57584, which changed state. Bug 57584 Summary: [4.9 Regression] ice: SSA corruption: Unable to coalesce ssa_names http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57584 What|Removed |Added Status|ASSIGNED|RESOLVED Resolution|--- |FIXED
[Bug tree-optimization/56982] [4.8 Regression] Bad optimization with setjmp()
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56982 Jakub Jelinek jakub at gcc dot gnu.org changed: What|Removed |Added Target Milestone|4.8.1 |4.8.2 --- Comment #12 from Jakub Jelinek jakub at gcc dot gnu.org --- GCC 4.8.1 has been released.
[Bug tree-optimization/56982] [4.8 Regression] Bad optimization with setjmp()
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56982 Bug 56982 depends on bug 57349, which changed state. Bug 57349 Summary: [4.9 Regression] ICE on 253.perlbmk with pgo after r198096 http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57349 What|Removed |Added Status|ASSIGNED|RESOLVED Resolution|--- |FIXED
[Bug tree-optimization/56982] [4.8 Regression] Bad optimization with setjmp()
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56982 Richard Biener rguenth at gcc dot gnu.org changed: What|Removed |Added Known to work||4.9.0 Summary|[4.8/4.9 Regression] Bad|[4.8 Regression] Bad |optimization with setjmp() |optimization with setjmp() --- Comment #11 from Richard Biener rguenth at gcc dot gnu.org 2013-04-19 13:40:05 UTC --- Author: rguenth Date: Fri Apr 19 13:39:16 2013 New Revision: 198096 URL: http://gcc.gnu.org/viewcvs?rev=198096root=gccview=rev Log: 2013-04-19 Richard Biener rguent...@suse.de PR tree-optimization/56982 * builtins.def (BUILT_IN_LONGJMP): longjmp is not a leaf function. * gimplify.c (gimplify_call_expr): Notice special calls. (gimplify_modify_expr): Likewise. * tree-cfg.c (make_abnormal_goto_edges): Handle setjmp-like abnormal control flow receivers. (call_can_make_abnormal_goto): Handle cfun-calls_setjmp in the same way as cfun-has_nonlocal_labels. (gimple_purge_dead_abnormal_call_edges): Likewise. (stmt_starts_bb_p): Make setjmp-like abnormal control flow receivers start a basic-block. * gcc.c-torture/execute/pr56982.c: New testcase. Added: trunk/gcc/testsuite/gcc.c-torture/execute/pr56982.c Modified: trunk/gcc/ChangeLog trunk/gcc/builtins.def trunk/gcc/gimplify.c trunk/gcc/testsuite/ChangeLog trunk/gcc/tree-cfg.c
